In one of water purifier systems, there is a water purifier system using a reverse osmosis membrane, a nanofiltration membrane or the like, and liquid separation devices such as spiral type, flat membrane type and hollow fiber type have been known. The spiral type liquid separation device has been used most widely because it can ensure a large membrane area in a given volume and treat in high efficiency.
As an ordinary spiral type liquid separation device shown in FIG. 7, a permeated liquid flow channel material 1 is sandwiched with separation membranes 2, further a feed flow channel material 3 is disposed on the outer side of the separation membrane 2 to form a set of units; and for the permeation side of the separation membrane to communicate, the unit or a plurality of the unit is wound around a hollow center tube 5 on that water collection holes 4 are arrayed.
The permeated liquid flow channel material 1 has been using a fabric where a crest and a groove are formed on its surface. As the fabric where a crest and a groove are formed on the surface, conventionally, warp knit fabric such as tricot has generally been used. In the case of tricot knit fabric, as shown in FIG. 5 (plan view) and FIG. 6 (C-C cross sectional view of FIG. 5), in a cross section perpendicular to a knitted loop direction (Y direction in FIG. 5, namely warp direction), a part that the knitted loop (needle loop 7) is present forms a linear crest 11 and supports the separation membrane, and a region between knitted loops (sinker loop 8) forms a linear groove 10, thereby to produce a flow channel of permeated liquid passed through the separation membrane.
Ordinarily, in the case of conducting desalination of sea water or separation of concentrated solutions such as fruit juice concentration efficiently by a liquid separation device using a reverse osmosis membrane as a separation membrane, a pressure is loaded so that a differential pressure of 5 to 10 MPa between the feed side and permeated liquid side is yielded. For preventing deformation of a permeated liquid flow channel material due to this pressure, the permeated liquid flow channel material is stiffened. A method that an epoxy resin or melamine resin is soaked, or melt-binding that fibers are stiffened by melt each other though heating is commonly known as the stiffening. Further, in the case where a convex part of the permeated liquid flow channel material is not flat, a fabric of the permeated liquid flow channel material is subjected to calendering because a reverse osmosis membrane may be deformed locally or nonuniformly under high pressure.
Further, there is proposed a method where a substance that a flat fabric is laminated to stiff on a fabric that a linear crest and a linear groove were formed and is used as a permeated liquid flow channel material (for example, see Patent document 1). By such constitution, a reverse osmosis membrane does not fall in because the reverse osmosis membrane is supported by the flat surface. Further, there is proposed a method that by using a double tricot as a permeated liquid flow channel material, namely by providing a flow channel on both surfaces of a flow channel material, flow channels are increased and flow channel resistance is decreased (for example, see Patent document 2). However, the former method of laminating a flat fabric poses a problem that constituent materials and production processes increase, deteriorating a production efficiency. On the other hand, the latter method that flow channels are provided on both surfaces of a flow channel material by using a double tricot also poses a problem that the number of units capable of being inserted into a module decreases because the total thickness becomes large, and deteriorating a treatment efficiency. Since tricot cannot narrows the width of a linear crest, it is not possible to increase the number of channels per unit width of a flow channel material. Therefore, the channel width must be widened to reduce the flow channel resistance of permeated liquid; by doing so, there is a problem that a reverse osmosis membrane undergoes a creep deformation with time and falls in.
Patent document 1: Japanese Unexamined Patent Publication No. 2000-342941 (p. 2 to 6)
Patent document 2: Japanese Unexamined Patent Publication Hei 9-141060 (1997) (p. 2 to 6)